Vortex separator

ABSTRACT

A multiple vortex separator or hydro cyclone, particularly for separating or cleaning fibrous suspensions, as for instance paper stock, including a plurality of individual separator units working in parallel. Each individual separator unit has an elongate external casing, which encloses the vortex chamber and has sealed axial ends and a uniform external cross-sectional profile over its entire length. Preferably, the external casing of the individual separator units is cylindrical. The individual separator units extend completely through the reject, inject and accept compartments in aligned openings in the walls between the compartments and the outer end walls of the reject and accept compartments respectively, so that the axial ends of the separator units are accessible from the outside at said outer walls of the accept and reject compartments respectively, and so that the separator units can be moved axially into and out of the compartments for replacement of the individual separator units. Such replacement of the individual separator units is possible during continued operation of the separator.

United States Patent [191 Skardal VORTEX SEPARATOR Primary Examiner Frank W. Lutter Assistant Examiner-Ralph J. Hill Inventor: Karl Arvid Skardal, Stocksund,

Swedenv Attorney, Agent, or FirmWaters,'Roditi, Schwartz & Nisson [73] Assignee: AB Fractionator, Stockholm, I

Sweden ABSTRACT 22 Filed: Oct. 25, 1973 21 Appl. No.: 411,355

U r a D. n

b c y c 0 r in r O r O t a r a p c S X e t r 0 v Foreign Application Priority Data Nov. 6, 1972 Sweden axial ends and a uniform external cross-sectional profile over its entire length. Preferably, the external casing of the individual separator units is cylindrical. The individual separator units extend completely through the reject, inject and accept compartments in aligned openings in the wallsbetween the compartments and the outer end walls of the reject and accept compartments respectively, so that the axial ends of the separator units are accessible from the outside at said 5 M98 l 52 6 2 Hi5 U SW0 3 5 4 7 a/ SB 5 2 m l u 5 u u 0 n l a 2 n l m 1 n n m m w m m 2 w W m" S u m Tm 3 n 7 u u 9 u m l ms l 21C m t .M W 5 mm S U IF l. .l] 2 8 5 55 l rll References Cited UNITED STATES PATENTS I outer walls of the accept and reject compartments re- 209/2 spectively, and so that the separator units can be 5 7 M X moved axially into and out of the compartments for FOREIGN PATENTS OR APPLICATIONS- ODell et a1.

In ""1. "n6 n em S h n k Hi-W. W J F 388 6667 9999 llll //l 1328 l 0044 11973 L 3 4 5oo 77 9 3333 replacement of the individual separator units. Such replacement of the individual separator units is possible during continued operation'of the separator.

209/144 209/144 Netherlands........................ 13 Claims, 6 Drawing Figures Australia.............................

PATENTED JANE] I975 SHEET 1 0? 2 PATENTED JANE 1 9 SHEET 2 OF 2 VORTEX SEPARATOR BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to vortex separators also called hydro cyclones, in particular for cleaning or separation of fibrous suspensions of the type which includes a plurality of individual separators or cyclones. Each includes an at least a partially conical vortex chamber provided at its larger end with at least one substantially tangential inlet for the suspension to be treated. The so called inject, and an axial outlet for a lighter or overflow-fraction, the so callled accept, of the treated suspension, and at its smaller end with an axial outlet for a heavier or .underflow fraction, the so called reject, of the treated suspension, and further a common.

inject compartment for the suspension to be treated communicate with the inject inlets of all individual separators. common accept compartment for the lighter fraction communicates with the accept outlets of all individual separators aswell as a common reject com partment for-the heavier fraction communicating with common serious disadvantage that it is a comparatively complicated and time-consuming task to remove and replace'an individual separator unit and that this requires that the operation of the entire separator apparatus is stopped. Further, in the majority of the prior art multiple vortex separators it is not possible during continued operation, to clean or clear 'an individual separator unit which has'been put out of operation due to clogging of its reject outlet and/or its inject inlet. In those-few prior art multipleseparators in which a clearing of the rejectoutletsof the. individual separator units ispossible during continued operation, this must be done .in such a manner thata leakage of liquida'nd suspension from these parator can hardly'be prevented and that there is a very considerable risk that the reject material accumulated in the clogged separator unit is transferred into the accept fraction soas to contaminate this. In most prior art separators, it'is-also impossible to observe during operation, whether an individual separator unit has been clogged.'The clogging of one or several of the individual separator units in the separator can in this case be detecte d'only from the resulting re-' fore to provide an improved multiple vortex separator of the'general type described in the foregoing. For this purpose the invention provides a vortex separator, in particular for separationor cleaning of fibrous suspension, comprising a plurality of individual separator units, each including an at least partially consubstantially tangential inject inlet for the suspension to be treated, the so-called inject, and an axial accept outlet for a lighter'fraction, the so-called accept, of the treated suspension and at its smaller end an axial reject outlet for a heavier fraction,.the so-called reject, of the treated suspension; a common inject compartment for the suspension to be treated communicating with the inject inlets of all said individual separator units; a common accept compartment for the lighter fraction communicating with the accept outlets of all said individual separator units; and 'a common reject compartment for the heavier fraction communicating with the reject outlets of all said individual separator units; said compartments being arranged side by side with the reject compartment and the accept compartment located on opposite sides of the inject compartment; and characterized in that each of said individual separator units has an elongate outer casing, which encloses the conical vortex chamber and has sealed opposite axial ends and a uniform external crosssectional profile over the entire length of the casing, that each individual separator unit extends completely through said reject, inject and accept compartments in aligned openings in the walls between the inject compartment and the reject and accept compartments respectively, and in the outer walls of the reject and accept compartments furthest removed-from the inject compartment, so that both axial ends of the separator units are accessible from the outside at said outer walls of the reject and accept compartments respectively, and the separator units can be pushed axially into or out of said compartments through said openings in said walls, and that the wall of the casing of each separator unit is provided with at least one reject port in the portion of the separator unit located within said reject compartment and communieating with the reject outlet of the vortex chamber of the separator unit, at least one inject port in the portion of the separator unit located within said inject compartment and communicating with the inject inlet of the vortex chamber of the separator'unit, and at least one accept port in the portion of the separator unit located within said accept compartment and communicating with the accept outlet of the vortex'chamber of the separator unit.

The most important advantage of the vortex separator, according to the invention, resides therein that it is possible in a simple and rapid manner to remove and replace an individual separator unit without any interruption of the operationof the separator. An individual separator unit which has been put out of operation, for instance, due to clogging or any other reason, can consequently be replaced with a new separator unit during continued operation of the separator and without any extensive disassemblingiand reassembling.

Another advantage of thevortex separator, according to the invention,is that it is possible during contin ued operation of the separator to observe visually the reject outlet as well as the accept outlet in each individual separator unit, whereby it is possible to detect very rapidly any clogging of the reject outlets as well as the inject inlets of the individual separator units. It is then being possible, as explained above,'to replace a clogged separator unit rapidly and easily with a new unit. 7

The vortex separator, according to the invention, has also a comparatively simple structural design and requires relative to its capacity less space, both with respect to floor space and height to ceiling, than prior art multiple vortex separators.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention will be further described with reference to the accompanying drawings, which show by way of example some preferred embodiments of a vortex separator according to the invention. In the drawings:

FIG. 1 is an end view, partially in section, of a first embodiment of a vortex separator according to the invention, the section being taken along the line II in FIG. 2;

FIG. 2 is a side view, partially in section, of the separator shown in FIG. 1, thesection being taken along the line IIII in FIG. 1;

FIG. 3 shows on a larger scale, and in axial section, an individual separator unit in the separator shown in FIGS. 1 and 2;,

FIG. 4 is a side view, similar to the one in FIG. 2, of a vortex separator according to the invention provided with means for diluting the reject;

FIG. 5 shows a cross-section through the separator in I FIG. 4 along the line VV in FIG. 4; and

FIG. 6 shows on a larger scale and in similar manner to FIG. 3, how an individual separator unit is mounted in the common inject, accept, reject and dilution liquid compartments in the vortex separator shown in FIGS. 4 and 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS vided with a pipeconnection 9, l0 and 11, respectively,

to each of the compartments 6, 7 and 8'respectively. In the illustrated embodiment, the end walls 2 and 3 and the internal partition walls 4 and 5 of the vessel 1 are square and project consequently partially outside the cylindrical shell of the vessel. This facilitates the installation of the vessel. As seen in the drawings, the vessel 1 is resting on bed beams 12 and 13 with angle irons 14 and 15 respectively, which are attached along one side of the square external walls 2 and 3. In the embodiment illustrated in the drawings, the vessel 1 is arranged with its pipe connections 9, l0, l1 pointing downwards, but it is obvious that the vessel could just as well be mounted on a support bed with the pipe connections pointing upwards or to the one or the other side. In this way the position of the vessel 1 can readily be adapted to the most suitable arrangement in the surrounding plant of the pipe conduits 1'6, 17 and 18 respectively connected to the pipe connections 9, l0 and 11.

The individual separator units 23 of the separator are mounted in the vessel 1, side, by side with their longitudinal axes mutually parallel, and parallel to the axis of the vessel 1. As most readily seen in FIG. 3, the separator units extend completely through the'vessel 1 in aligned openings'19, 20, 21 and 22 in the walls 2, 4,5 and 3 respectively of the vessel. In the illustrated embodiment, the vessel 1 is designed to hold 121 individual separator units. As shown in FIG. 3, each individual separator unit 23 is shaped as an elongate cylinder having a smooth cylindrical external wall with a uniform diameter over the entire length of the unit. Consequently, each individual separator unit can separately,

' and in a very simple manner, be pushed into or out of the vessel 1 respectively through the openings 19 to 22 provided for the separator unit in the vessel walls 2 to 5. The necessary sealing between the vessel walls 2 to 5 and the separator units 23 at the openings 19 to 22 in the vessel walls is in the illustrated embodiment provided for by seal rings 24 of suitable elastic material, which are inserted in the openings 19 to 22 and seal against the surface of the separator'units 23. In the illustrated embodiment, these seal rings 24 have such a design that they are pressed against the surface of the separator units 23 by the liquid pressure existing within the compartments 6, 7 an 8 during operation of the separator. The friction between the seal rings 24, and the external wall of the separator units 23, is sufficiently small, however, soar not to prevent the axial displacement ofthe separator units into and out from the vessel 1.

As shown in detail in FIG. 3, each individual separator unit 23 comprises a cylindrical, substantially tubular central body 25, provided with two ducts 26 passing through its wall and having tangentially directed orifices into the interior of the central body 25 at one side of an internal transverse wall 27. The transverse wall 27, is provided with a central axial bore 28, to which a relatively short tubular piece 29 is connected on the one side of the wall 27 and a relatively longer tubular piece 30 is connected on the opposite side of the wall 27. The two tubular pieces 29 and 30 are preferably integral and may also be integral with the transverse wall 27. A substantial conical tube 31 is joined with its larger end to the one axial end of the central body 25. The conical tube 31- is connected tothe central body 25 by means of a tubular cylindrical sleeve 32, which has the same external diameter as the central body 25, and which is attached to the central body 25 by means of a threaded connection 33. The tubular sleeve 32 en-' closes the conical tube 31 and extends axially past its narrow end. The outer end of the sleeve 32 is sealed by an end plate 34, kept in place by a lock ring 35, screwed into an internal thread 36 at the end of the sleeve 32. A similar tubular cylindrical sleeve 37 having the same external diameter as the central body 25 is connected to the other axial end of the central body 25 by means of a threaded connection 38. The sleeve 37 encloses the tube 30 and extends. axially past the end of the tube 30. The outer end of the sleeve 37 is sealed by an end plate 39 kept in place by an externally threaded short sleeve 40, which is screwed into an internal thread 41 in the outer end of the sleeve 37. Adjacent its outer end the tubular sleeve 32 is provided with two radial ports 42, through which the interior of the sleeve 32 communicates with the compartment 6 in the vessel 1. In similar manner, the tubular sleeve 37 is adjacent its outer end, provided with two ports 43 through which the interior of the sleeve 37 communicates with the compartment 8 in the vessel 1.

This separator unit 23 operates in a manner well known in the art. The conical tube 31 forms a substantially conical vortex chamber 44, which receives at its larger end the suspension to be cleaned or separated, the so called inject, through the tangential ducts 26,

which consequently serve as inject inlets to the vortex chamber 44 and through which the inject is fed into the vortex chamber fromthe compartment 7 in the vessel 1. Consequently, the compartment 7 in the vessel 1, serves as a common inject compartment for all separator units 23, to which inject compartment the inject suspension is supplied through the pipe conduit 17 and the pipe connection 10. Within the vortex chamber 44, the suspension forms in well known manner a helical vortex, in which the suspension is separated in a heavier fraction, the so called reject, concentrated close to the wall of the vortex chamber and a lighter fraction, the so called accept, close to the center of the vortex. The reject, that is the heavier fraction, is discharged from the vortex chamber 44 through its narrow open end 45, which consequently serves as a reject outlet from the vortex chamber 44. From this reject outlet 45, of the vortex chamber 44, the reject flows through the openings 42 in the wall of the tubular sleeve 32 into the compartment 6 in the vessel 1. Consequently, this compartment 6 serves as a common reject compartment for all separator units 23, from which a reject compartment the rejcect is withdrawn through the pipe connection 9 and the pipe conduit 16. The accept, that is the lighter fraction, is discharged from the vortex chamber 44in well known manner through the short tube 29, which serves as a vortex finder, and the openings 28in the transversewall 27 at the larger end of the vortex chamber 44. Consequently, the accept flows through the tube 30 and its open end 46 and subsequently, through the openings 43 in the sleeve 37 into the compartment 8 in the vessel 1. Consequently, the compartment 8 serves as a common accept compartment for all separator units 23, from which accept compartment the accept is withdrawn through the pipe connection 11' and the pipe conduit 18.

The-"two end plates 34 ad 39 consist preferably of a transparent material so as'to form windows, through which the suspension flow at the reject outlet 45 from the vortex chamber 44, and at the open end 46 of the accept outlet tube 30 respectively, can be observed from the outside during operation of the separator. It

is, consequently, possible to detect by observation through the window 34, if the reject outlet should become clogged by solid material. Through the other window 39, it is possible to detect if the inject inlet 26 to the vortex chamber 44, should become clogged. A clogging of theinject inlet 26 to the vortex chamber 44, will give cause to a characteristic, and readily observable change, in the suspension flow at the open end 46 of the tube 30; the suspension flow being interrupted if the liquid pressures in the accept and reject compartments 8 and 6respectively are the same; the suspension flow becoming laminar instead of vortical if the liquid pressure in the reject compartment is higher than in the accept compartment; and the suspension flow changing direction if the pressure is higher in the accept compartment than in the reject compartment. If such a clogged, and consequently no longer operating separator unit is detected, it can, as described in the foregoing, easily and rapidly be removed from the vessel 1 and replaced with a new separator unit.

Special arrangements are made in order to make from the vessel 1 through the openings 19 and 22 in the end walls 2 and 3 of the vessel. Thus, the end plate 34 of the separator unit 23, is provided with a threaded plug or screw 47 mounted in a threaded bore in the plate 34 and having its inner end shaped as a valve disc 47a, which can be brought to seal the reject outlet 45 from the vortex chamber 44 in that the plug 47 is screwed inwards. In this way the communication between the reject outlet 45 of the vortex chamber 44, and the openings 42 in the tubular sleeve 32 can be interrupted. In similar manner the other end plate 39 of the separator unit, is provided with a threaded plug 48 mounted in a threaded bore in the plate 39 and provided at its inner end with a valve disc 48a, which can be brought to seal the accept outlet 46 from the vortex chamber 44 in that the plug 48 is screwed inwards. In this way, the communication between the vortex chamber 44 and the openings 43 in the wall of the tubular sleeve 37 can be interrupted. Further, the internal thread 36 at the outer end of the sleeve 32, is complementary or identical to the internal thread 41 at the outer end of the other tubular sleeve 37 and fits consequently the external thread on the short sleeve 40. Consequently, the reject end of one separator unit can be joined to the accept end of another separator unit, in that the first unit is screwed with the internal thread 36 at its reject end onto the sleeve 40 at the accept end of the second separator unit.

For the replacement of a separator unit mounted in the vessel 1 with a new separator unit the rejectoutlet, as well as the accept outlet, in both separator units are sealed by means of the plugs 47 and 48 in the respective separator units. Thereafter, one end of the new separator unit is joined with the opposite end of the separator unit mounted in the vessel 1 in the manner described above, whereafter the separator unit mounted in the vessel 1 can be pushed out from the vessel at the same time-as the new separator unit is pushed into the same place in the vessel 1. Thereafter, the replaced separator unit is disconnected from the new separator unit, which is now mounted in the vessel 1 and which can be put into operation in that its plugs 47 and 48 are screwed outwards so that the reject outlet and accept outlet of the unit are openedand put into communication with the reject compartment 6 and the accept compartment 8 respectively. It is appreciated that such a replacement of a separator unit with a new separator unit can be carried out in short time and in a very simple way without any leakage of suspension or liquid from the vessel 1 or any overflow of liquid or suspension between the different compartments 6, 7 and 8 in the vessel.

It is also appreciated that if one wishes only to re- .move a separator unit-from thevessel 1 without replacing it with a new separator unit, this can be done in that a solid cylindrical rod or tube is coupled to one end of the separator unit and pushed into its place in the vessel 1 at the same time as the separator unit is pulled out from thevessel.

It is also appreciated that if one wishes only to put some separator units in the vessel 1 out of operation, for instance for reducing the total capacity of the apparatus, this can be done by closing the reject and accept outlets of said separator units by means of the screw plugs 47 and 48.

In the separator unit 23 illustrated by way of example in FIG. 3, the tubular sleeves 32 and 37 and also the end plates 37 and 39 with the valve plugs 47 and 48 are identical to each other, which reduces the costs for the manufacture and stock-keeping of parts for the separator units.

From the foregoing, it is obvious that the illustrated embodiment of a vortex separator apparatus, according to the invention, requires a comparatively small floor space as it has to be accessible only at the end walls 2 and 3 of the vessel 1. Further, the necessary height to ceiling is limited to a height corresponding to the diameter of the vessel 1, or the height necessary for the operating personnel.

It is appreciated, that in addition to the embodiment of the invention described in the foregoing, with reference to the drawings, also many other embodiments of vortex separators are possible within the scope of the invention. This is, in particular, the case for the detailed structural design of the individual separator units, which can vary within wide limits. Thus, it is fundamentally not necessary that the individual separator units have a cylindrical external shape, even if this should be the most practical one in most cases. Essential is only that the outer casing of the individual separator units has a uniform external cross-sectional pro file over its entire length, so that the separator units can readily be pushed into and pulled out from the common vessel through the openings in the end walls and the partition walls of the vessel. Thus for instance, the separator units may instead of a circular cross-section, have an elliptical or polygonal cross-section. Further, it is also possible to mount the vessel 1 with its axis vertical, and consequently with the separator units vertical, in which case, however, means must be provided for retaining the separator units in axial direction in the vessel 1. Such an arrangement would, however, probably make thereplacement of the separator units in the separator somewhat more complicated. Further, it is of course not necessary that the inject compartment, the reject-compartment and the accept compartment are joined to form an integral vessel as in the embodiment of the invention described in the foregoing, but these compartments couldalso be erected separately, side by side, possibly somewhat spaced from each other. In

most cases, however, such an arrangement would not give any particular advantages. In the embodiment of the invention described in the foregoing, with reference to the drawings, the reject, inject and accept compartments, have a plane-parallel shape with the individual separator units mounted with their longitudinal axes mutually parallel. It could also be contemplated, however, to design the accept, inject and reject compartments, as annular concentric compartments formed by concentrically mounted cylinders, in which case the individual separator units would extend radially through the concentric annular compartments. In order to make a replacement of the individual separator units possible in a manner similar to the one described in the foregoing, it would in a separator designed in this way obviously be necessary to provide an accessible central shaft inside the concentric annular compartments having a diameter at least corresponding to the length of an individual separator unit. Further, such a separator must obviously be accessible from'all sides along its entire periphery, if a replacement of the individual separator units is to be possible. Such a separator will therefore require a much larger floor space than a separator designed as shown in FIGS. 1 to 3 and described in the foregoing.

A problem that may arise in a separator designed as described in the foregoing and illustrated in FIGS. 1 to 3, particularly when used for cleaning or separating fibrous suspensions, is caused by the fact that the heavier fraction, the so called reject, which is discharged from the individual separator units 23 into the common reject compartment 6, may have a comparatively thick and viscous consistency. This may cause that the reject flow within the reject compartment from the individual separator units to the discharge opening from the reject compartment will no longer be uniform in all parts of the reject compartment but may cease completely in some parts of the reject compartment. It is realized that the result will be that the separator units located in these parts of the reject compartments are put out of operation. The risk of such flow stoppages in some parts of the reject compartment is increased by the fact that space within the reject compartment is to a large part occupied by the separator units through the reject compartment, wherefore the flow paths for the reject between these separator units are comparatively restricted. This problem can in principle be solved in that the consistency of the reject is reduced by addition of a dilution liquid, that is pure water when treating a paper stock. This requires, however, that the dilution liquid can be distributed in a well-defined manner to those parts of the reject compartment where it has been found that flow stoppages easily occur.

This is achieved in a very efficient and simple way in a vortex separator designed as illustrated in FIGS. 4 to 6.

The vortex separator illustrated in FIGS. 4 to 6 comprises just as the separator illustrated in FIGS; 1 to 3 a cylindrical vessel 1, which has plane parallel end walls 2 and 3 and which is divided in an inject compartment 7, an accept compartment 8, and a reject compartment 6 by plane internal partition walls 4 and 5. In the apparatus of FIGS. 4 to 6, however, the vessel I is provided with an additional internal partition wall 49 so that the vessel contains an additional compartment 50, which is located between the inject compartment 7 and the reject compartment 6 and which is used for supplying dilution liquid to the reject. The dilution liquid is fed into the compartment 50 through a pipe connection 51.

The individual separator units 23 extend through the vessel 1 in the manner described in the foregoing and as illustrated with dotted lines in FIG. 4 for a single separator unit. Consequently, each individual separator unit 23 extends through all compartments 6, 7, 8 and 50 in the vessel,-and through aligned openings in all walls of the vessel, that is the partition walls 4, 49, 5 as well as the end walls 2 and 3. The openings for the separator unit 23 in the additional partition wall 49 are designated with 52. In the same manner as in the separator described in the foregoing and illustrated in FIGS. 1 to 3, the individual separator units have their inject ports 26 located within the inject compartment 7, their accept ports 43 located within the accept compartment 8, and their reject ports 42 located within the reject compartment 6. Within the additional dilution liquid compartment 50 the separator units 23 have no openings at all. The openings 22 in the end wall 3, the openings 21 in the end-wall 5, the openings 52 in the additional partition wall 49 and the openings 19 in the outer end wall 2 are sealed by means of suitable seal rings 24 sealing against the outer surface of the separator units 23 in the same way as in the separator shown in FIGS. 1 to 3. I

In the openings 20 for theseparator units 23 in the partition wall 4 between the dilution liquid compartment 50 and the reject compartment 6, however, seal rings are omitted for at least some of the separator units, as shown in FIGS. 5 and 6, wherefore at these separator units an annular clearance or flow passage exists from the dilution liquid compartment 50 to the reject compartment along and about the surface of the separator unit 23. Consequently, during operation of the separator, dilution liquid fed into the dilution liquid compartment 50 through the feeder pipe 51 will from the compartment 50, flow into the reject compartment 6 through the openings 20 in the partition wall 4 along and about those separator units 23 which are not provided with any seal rings in the openings 20, as indicated by arrows 53 in FIG. 3. It is appreciated that at these separator units 23 the dilution liquid from the compartment 50 will flow into the reject compartment 6 along the outer surface of the separator units, whereby the dilution liquid keeps the reject ports 42 of the separator units clear so that any clogging of these reject ports is prevented, and the dilution liquid will also dilute the reject in the adjacent portions of the reject compartment 6 so that the reject can flow more easily towards the outlet 16 of the reject compartment 6.

As illustrated in FIG. 5, it isin most cases not necessary or preferable to feed dilution liquid into the reject compartment 6 at all separator units 23. It may be preferable to seal the openings 20 in the partition wall 4 between the reject compartment 6 and the dilution liquid compartment 50 at some of the separator units 23, in the same way as in the separator disclosed in FIGS. 1 to 3, whereas at other separator units these seal rings areomitted, as described above, so that dilution liquid from the compartment 50 is fed into the reject compartment 6-at' these latter separator units. Thus, as shown by way of example in FIG. 5, dilution liquid may be fed int'othe reject compartment 6 only at some of the separator units 23, whereas at the remaining separator units no dilution liquid is fed into the reject compartment 6. The separator units 23, at which dilution liquid is fed into the reject compartment, are framed by a dash-dotted line in FIG. 5. The separator units, at which dilution liquid is to be fed into the reject compartment in the manner described, are selected onthe basis of operation experiences so that the dilution liquid is fed into those parts of the reject compartment where it has been noticed that stoppages in the reject flow easily occur. Generally it is preferable, as shown by way of example in FIG. 5, to feed the dilution liquid into those parts of the reject compartment which are furthest away from the outlet 16 from the reject com partment, as stoppages in the reject flow occur most often in these remote parts of the reject. compartment. From the foregoing it is appreciated that the embodiment of a vortex separator according to the invention illustrated in FIGS. 4 to 6 has a very simple and unexpensive structural design and that it makes it very easy to select those partsof the reject compartment into which dilution liquid shall be fed, on the basis of tests and operation results.

It is also appreciated that the arrangement. described above for supplying dilution liquid to the reject compartment does not cause any other changes in the fundamental design and mode of operation of the separator or in its other advantages.

What is claimed is:

l. A vortex separator, particularly for separating fibrous suspensions, comprising a plurality of individual separator units, each including an at least partially conical vortex chamber having at its larger end at least one substantially tangential inject inlet for the suspension to be treated and an axial accept outlet for a lighter fraction of the treated suspension and at its smaller end an axial reject outlet for a heavier fraction of the treated suspension; a common inject compartment for the suspension to be treated communicating with the inject inlets of all said individual separator units; a common accept compartment for said lighter fraction communicating with the accept outlets of all said individual sep-' arator units; and a common reject compartment for said heavier fraction communicating with the reject outlets of all said individual separator units, said compartments being arranged side by side with said reject and accept compartments located on opposite sides of said inject compartment, each of said individual separator units having an elongated external casing enclosing said conical vortex chamber and having sealed axial ends and an uniform external cross-sectional profile over its entire length, each individual separator unit extending completely through .said reject, inject and accept compartmentsin aligned openings in the walls between the inject compartment and the reject and accept compartments respectively, and in the outer walls of the reject and accept compartments furthest removed from the inject compartment, whereby both axial ends of the separator units are accessible from the outside of saidouterwalls of the reject and accept compartments and the separator units can'be pushed axially into and out from said compartments through said openings in the compartment walls, the external casing of each separator unit being provided with at least one reject port communicating with the reject outlet of the vortex chamber and positioned in the portion of the separator unit located within the reject compartment, at least one inject port communicating with the inject inlet of the vortex chamber and positioned in the portion of the separator unit located within the inject compartment, and at least one accept port communicating with the accept outlet of the vortex chamber and positioned in the portion of the separator unit located within the accept compartment.

2. A vortex separator as claimed in claim I, wherein said reject, inject and accept compartments are parts of a common vessel having two substantially plane and parallel outer walls for the reject compartment and the accept compartment respectively, and two internal plane partition walls parallel to said outer walls between the inject compartment and the reject and acpling means, said first and second coupling means being complementary, so that one end of a first separator unit can be connected to the opposite end of a second separator unit by means of said first and second coupling means respectively, provided at said ends of said first and second separator units, whereby a separator unit can be removed from said reject, inject and accept compartments and replaced with a new separator unit in that one'end of said new separator unit is connected to the opposite end of said first mentioned sepa-' rator unit and subsequently pushed into said compartments, at the same time, as the first mentioned separator unit is pushed out from the compartments.

5. A vortex separator as claimed in claim 1, wherein each of said'individual separator units is provided with two valve means operable from the outside of the opposite axial ends ofthe separator unit for shutting off respectively the communication between the reject outlet of the vortex chamber, and the reject port in the external casing of the separator unit and the communication between'the accept outlet of the vortex chamber and the accept port in the external casing of the separator unit.

6. A vortex separator as claimed in claim 5, wherein said valve means include threaded plugs screwed into aixal threaded bores in the axial end walls of the external casing of the separator unit and provided at their inner ends with valve discs adapted to close the reject outlet and the accept outlet of the vortex chamber respectively when the threaded plugs are screwed inwards into the separator unit.

7. A vortex separator as claimed in claim 1, wherein the axial end walls of the external casing of the separator unit are transparent.

8. A vortex separator as claimed in claim 1, comprising an additional compartment provided with an inlet for feeding a dilution liquid into the compartment, said additional compartment being located next to said reseparator units, are provided with said annular flow passages, whereas the openings provided in said partition wall for all other separator units are sealed against the outside of the separator units extending therethrough, said predetermined group of separator units comprising those separator units which are located furthest away from the reject outlet from said reject compartment.

10. A vortex separator, as claimed in claim 8, wherein said additional compartment is located between said reject compartment and said inject compartment.

11. A vortex separator, as claimed in claim 1, wherein said external casing of each individual separator unit is cylindrical with a constant diameter over the entire length of the casing.

12. A vortex separator as claimed in claim 11, wherein each individual separator unit comprises a cylindrical, substantially tubular central body forming a central portion of the cylindrical casing of the separator unit, and having an internal transverse wall provided with a central axial aperture and in its circumferential wall at least one flow duct extending substantially tangentially from the outside of the central body to the interior of the central body on one side of said transverse wall; a conical tube forming said vortex chamber and joined with its larger end to the axial end of said central body located on said one side of said transverse wall; a first cylindrical tubular sleeve having the same external diameter as said central body and attached at one end to said axial end of said central body so as to enclose said conical tube and extending at its opposite end axially past the smaller end of said conical tube; a first end plate sealing said opposite end of said first tubular sleeve; a second cylindrical tubular sleeve having the same external diameter as said central body and connected at its one end to the opposite axial end of said central body; and a second end plate sealing the opposite end of said second tubular sleeve; each of said first and second tubular sleeves being provided with at least one aperture in its wall adjacent said opposite end of the sleeve.

13. A vortex separator as claimed in claim 12, comprising a tube having substantially the same inner diameter as said central aperture in said transverse wall of saidcentral body and extending from said transverse wall within said second tubular sleeve to a point adjacent but axially spaced from said second end plate. 

1. A vortex separator, particularly for separating fibrous suspensions, comprising a plurality of individual separator units, each including an at least partially conical vortex chamber having at its larger end at least one substantially tangential inject inlet for the suspension to be treated and an axial accept outlet for a lighter fraction of the treated suspension and at its smaller end an axial reject outlet for a heavier fraction of the treated suspension; a common inject compartment for the suspension to be treated communicating with the inject inlets of all said individual separator units; a common accept compartment for said lighter fraction communicating with the accept outlets of all said individual separator units; and a common reject compartment for said heavier fraction communicating with the reject outlets of all said individual separator units, said compartments being arranged side by side with said reject and accept compartments located on opposite sides of said inject compartment, each of said individual separator units having an elongated external casing enclosing said conical vortex chamber and having sealed axial ends and an uniform external cross-sectional profile over its entire length, each individual separator unit extending completely through said reject, inject and accept compartments in aligned openings in the walls between the inject compartment and the reject and accept compartments respectively, and in the outer walls of the reject and accept compartments furthest removed from the inject compartment, whereby both axial ends of the separator units are accessible from the outside of said outer walls of the reject and accept compartments and the separator units can be pushed axially into and out from said compartments through said openings in the compartment walls, the external casing of each separator unit being provided with at least one reject port communicating with the reject outlet of the vortex chamber and positioned in the portion of the separator unit located within the reject compartment, at least one inject port communicating with the inject inlet of the vortex chamber and positioned in the portion of the separator unit located within the inject compartment, and at least one accept port communicating with the accept outlet of the vortex chamber and positioned in the portion of the separator unit located within the accept compartment.
 2. A vortex separator as claimed in claim 1, wherein said reject, inject and accept compartments are parts oF a common vessel having two substantially plane and parallel outer walls for the reject compartment and the accept compartment respectively, and two internal plane partition walls parallel to said outer walls between the inject compartment and the reject and accept compartments respectively, said individual separator units extending through said vessel with their longitudinal axes mutually parallel and substantially perpendicular to said walls of the vessel.
 3. A vortex separator as claimed in claim 2, wherein said vessel is cylindrical and supported with its axis horizontal.
 4. A vortex separator as claimed in claim 1, wherein each of said individual separator units is provided at its one axial end with first mechanical coupling means and at its opposite axial end with second mechanical coupling means, said first and second coupling means being complementary, so that one end of a first separator unit can be connected to the opposite end of a second separator unit by means of said first and second coupling means respectively, provided at said ends of said first and second separator units, whereby a separator unit can be removed from said reject, inject and accept compartments and replaced with a new separator unit in that one end of said new separator unit is connected to the opposite end of said first mentioned separator unit and subsequently pushed into said compartments, at the same time, as the first mentioned separator unit is pushed out from the compartments.
 5. A vortex separator as claimed in claim 1, wherein each of said individual separator units is provided with two valve means operable from the outside of the opposite axial ends of the separator unit for shutting off respectively the communication between the reject outlet of the vortex chamber, and the reject port in the external casing of the separator unit and the communication between the accept outlet of the vortex chamber and the accept port in the external casing of the separator unit.
 6. A vortex separator as claimed in claim 5, wherein said valve means include threaded plugs screwed into aixal threaded bores in the axial end walls of the external casing of the separator unit and provided at their inner ends with valve discs adapted to close the reject outlet and the accept outlet of the vortex chamber respectively when the threaded plugs are screwed inwards into the separator unit.
 7. A vortex separator as claimed in claim 1, wherein the axial end walls of the external casing of the separator unit are transparent.
 8. A vortex separator as claimed in claim 1, comprising an additional compartment provided with an inlet for feeding a dilution liquid into the compartment, said additional compartment being located next to said reject compartment and separated therefrom by a partition wall, which is provided with openings through which said individual separator units extend, at least some of said openings being provided with annular flow passages around the separator units extending through said flow passages, whereby dilution liquid can flow through said annular flow passages from said additional compartment into said reject compartment.
 9. A vortex separator as claimed in claim 8, wherein only those openings in the partition wall between the reject compartment and said additional compartment, which are associated with a predetermined group of separator units, are provided with said annular flow passages, whereas the openings provided in said partition wall for all other separator units are sealed against the outside of the separator units extending therethrough, said predetermined group of separator units comprising those separator units which are located furthest away from the reject outlet from said reject compartment.
 10. A vortex separator, as claimed in claim 8, wherein said additional compartment is located between said reject compartment and said inject compartment.
 11. A vortex separator, as claimed in claim 1, wherein said external casing of each individual separator unit is cylindrical with a constant diameter over the entire length of the casing.
 12. A vortex separator as claimed in claim 11, wherein each individual separator unit comprises a cylindrical, substantially tubular central body forming a central portion of the cylindrical casing of the separator unit, and having an internal transverse wall provided with a central axial aperture and in its circumferential wall at least one flow duct extending substantially tangentially from the outside of the central body to the interior of the central body on one side of said transverse wall; a conical tube forming said vortex chamber and joined with its larger end to the axial end of said central body located on said one side of said transverse wall; a first cylindrical tubular sleeve having the same external diameter as said central body and attached at one end to said axial end of said central body so as to enclose said conical tube and extending at its opposite end axially past the smaller end of said conical tube; a first end plate sealing said opposite end of said first tubular sleeve; a second cylindrical tubular sleeve having the same external diameter as said central body and connected at its one end to the opposite axial end of said central body; and a second end plate sealing the opposite end of said second tubular sleeve; each of said first and second tubular sleeves being provided with at least one aperture in its wall adjacent said opposite end of the sleeve.
 13. A vortex separator as claimed in claim 12, comprising a tube having substantially the same inner diameter as said central aperture in said transverse wall of said central body and extending from said transverse wall within said second tubular sleeve to a point adjacent but axially spaced from said second end plate. 